How to chuck a tenon with these jaws

**tonzeyd** · 4th June 2020, 10:15 PM

Probably bit late, but i'm a new turner and have only been using the above style chuck in tenon mode. As others have pointed out its important to match the taper of the dovetail jaws.

The other things i've noticed when using mine is to re tighten the jaws after you've roughed the bowl out especially if your blank was square or particularly off kilter. The vibrations when truing up the blanks seems to loosen the chuck enough that by the time you're almost done the slightest bump sends your nicely turned bowl flying. Tightening it up after rounding the blank has eliminated this from happening.

Plus I've found that you need to take much more off the blank that you realise the wood just below the bark is still soft and spongy. Turning a tenon using this layer is just playing with fire, a couple of extra mm off and its plenty strong even with a tenon thats only a few mm thick.

You can also use those jaws to clamp down on square blanks that fit inside the jaws, it'll squash the corners abit so you'll need to plan your blank accordingly and accept that you'll be losing about 5-10mm of your blank when you part off at the chuck end.

To answer your questions:
1) Yes, just try and match the taper of the jaws as close as possible
2) no difference, spigots are used for small blanks, while the pictured is used for bowls or larger blanks. Both essentially hold wood.

**LanceC** · 4th June 2020, 10:35 PM

Originally Posted by powderpost

As has already been mentioned, a waste piece screwed to a face plate and turned to suit the foot of your bowl, and glued bowl blank is far better imho.

Are you talking about a jam chuck? Also, can you expand on the glued bowl blank?

I have spent a fair portion of this evening researching online trying to understand what has been discussed.

So thank-you all for your input, this has been a steep, but fascinating learning curve.

**powderpost** · 4th June 2020, 11:24 PM

Originally Posted by LanceC

Are you talking about a jam chuck? Also, can you expand on the glued bowl blank?

Lance, Both jam chucks and glue chucks start by screwing a waste block, at least 19mm thick, to a face plate. For a jam chuck a recess is cut into the waste block. That recess needs to be a "jam" fit for a spigot or bowl to fit and have enough friction to hold the bowl firmly enough without glue, so that the bowl can be worked on. This method is often used to finish off the bottom of the bowl.

A glue chuck can be used after the back of the bowl has been turned and the foot size determined as before. The waste block fitted to the face plate is now turned to match the foot on the bottom of the bowl so that the they are exactly the same shape and size, so that the bowl can be centred. Imagine two saucers glued back to back. The idea is now to turn out the inside of the bowl.

As I mentioned in the previous post, this method allows you to determine the size and shape of the foot of the bowl and not be dictated to by a chuck. The down side is that you have to wait for glue to dry properly, or the outcome can be more that unsatisfactory. Don't ask!!!

Hope this is clear enough to get the picture.

Jim

**LanceC** · 5th June 2020, 08:38 AM

Excellent description Jim. Thanks for taking the time to explain it.

**Mobyturns** · 5th June 2020, 08:57 AM

Originally Posted by Jim Carroll

These jaws are the Nova shape jaws, best way is to close the jaws , measure the internal diameter and add 6mm,
This will then give you the diameter of the straight tenon you need to make. The tenon has to be shorter than the depth of the jaw so the bowl will sit on top of the jaws.
Once you have created the tenon, lay your skew chisel on its side on your toolrest and make a small indent at the base of the bowl for the notch to locate in, If you dont do this there is a good chance the bowl can slide out of the jaws.

Jim, these are not quite the same as the standard Nova style jaws which have a Triangular lip inside the jaws. The Axminster type C have a square shouldered lip. I use the same technique as you mention for the Nova style jaws. I've never liked the cylindrical inside profile and the high reliance on the "beak."

One thing that I commend though is the very well put together Teknatool jaw manual, probably the best and most descriptive in the industry. Well worth the read & turners should pay close attention to Teknatool's recommended max blank size and max recommended speeds for each jaw design.

https://www.teknatool.com/wp-content...ual_June08.pdf

**Dalboy** · 5th June 2020, 05:47 PM

Not sure of the brand that you have normally the Axminster sets have a 6 digit number on them. With this design internal jaws, the tenon needed to hold a piece is a straight tenon compared to the dovetailed used with many other chuck jaw designs. I have a number of their jaws, as I am in England they are very common here.

The Axminster C jaws have a tenon size around the 57mm (2.24") mark The same principle applies to the rest of the tenon as you would use in a dovetailed set

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